Load equalizing device for thrust bearings



March 3, 1953 2 =2 Q a Z 22 21 23 a .{5 25 13 Ill 34 f Ira E 77/67 F 17 Arzhur W. Barks MfW Patented Mar. 3, 1953 LOADEQUALIIZINGLDEVICE FOR 'rmws'r I BEARINGS i Arthur W.:.Burks,mD.ecatur, .Illl, assignor to Decatur Pump Compan v ration of Illinois y, Decatur,-Ill., a corpo AppIicationJuIyQ;1950, Serial No. 172,233 1c'1aim.ff.(c1.30s--160 The present invention relates to a load equalizing device for thrust bearings, and more particularly to meansfor individually apportioning the total thrust load imposed on the plurality of bearings. v i i In various environments, as in machine tools and the like, the thrust load imposed on a rotarymember is transmitted to a stationary housing or the likethrough a plurality of thrust bear- One thrust race of .each bearing is secured to the relatively movable member and the ings.

other race of the bearingisfixed with respect to the relatively fixed member. The load imposed upon any one of the thrust bearing races should be predetermined in orderlto insure the provision of a suitabletype and size bearing for the load which it must bear. However, the determination of the thrust load on a given hearing under these circumstances is extremely difficult due to the many factors of design and to the varying nature of the load imposed on the rotary member and to many other factors involved in the specific installation.

The present invention now provides improved means for individually apportioning the thrust load upon a plurality of bearings so that apredetermined proportion of the total thrust load will be imposed on each bearing. The present invention thus contemplates, in effect, the provision of a coupling between :the bearings for. accommodating the predetermined division of thrust loads between a plurality of bearings. In this manner, the thrust load which is to be imposed upon a given bearing may be determined prior to bearing installation, thereby preventing the failure of the bearing under load and obviating the necessity of carrying out the extremely complicated calculations heretofore necessary.

The means of the present invention are particularly adapted for employment in machine tools, such as routers and the like. The particular means of the present invention suitably include a generally cylindrical thrust collar confined between the stationary thrust race of a bearing and a stationary housing which journals the relatively rotatable member.

More particularly, the collar is in extended surface contact with a circularly arranged series of hemispherical rocker members, each seated in a saddle or cradle. The saddle or cradle is confined within the fixed housing for the rotary member. To apportion the load between two thrust bearings, each of the bearings is provided with a similar collar and each of the collars has a projection extending into contact with each rocker element of the composite rocker member I :so that the totalthrust load on therotary mem ber is received by the rocker member through the medium of the collar. The total thrust transmitted to the rocker member by the collar is the total thrust load imposed on the bearings for the rotary member, while at the same :time.

the rocker member transmits. to the housing the load imposed thereon. The total force trans-. mitted to the rocker member by any collar is 1 directly proportional to the radial distance be tweenthe center lined the projection on the.

collar and the center line of rotation of the. rocker member. Thus, the portion of the thrust load to be transmitted to the housing through each of the bearings is dependent upon and. di-

rectly proportional to the radial distance be tween the center line of the projection on the. collar and the; center line of rotation of the rocker member. It is, therefore, an important object of the present invention to provide an improved thrust load, equalizing device for a plurality of thrust bearings, the device having a rocker member, serving to apportion between a plurality of bearings the total thrust load imposed thereon.

Another object of the present inventionisto provide a load equalizing device fora plurality,

of thrust bearings including a rocker member confined within a saddle and means operatively connecting each of the. bearings with the rocker v member for transmitting the thrust load from the hearings to therocker member, said rocker.

member serving to apportion the total load on the bearings between the individual bearings.

Still another objectof the present invention is 'to provide means for apportioning the total thrust load between a plurality of concentric thrust bearings, the means including cylindrical thrust collars for each of the bearings, and a rocker member in surface contact with the collars, the rocker member apportioning the total load between the bearings. s

Other and further important objectsof this invention will be apparent from the disclosures in the specification and the accompanying drawings.

Figure 3 is an enlarged fragmentary. sectional view, similar to Figure 1 and illustrating one form of the device of the present invention;

Figure 4 is an enlarged fragmentary sectional view similar to Figure 1 and illustrating a modified form of the device of the present invention.

As shown on the drawings:

Reference numeral It refers generally to a machine tool router including a housing I I having an axial bore I2. A router spindle I3 is mounted in the bore I2 to extend axially therethrough.

The spindle I3 is rotatably journaled in the bore I 2 by suitable means, to be hereinafter more fully described, the spindle I 3 being axially bored as at I4 to receive therethrough an elongated tie bolt I5. A tool I6 is provided with a head I'I projecting beyond the spindle I3 and with a rearwardly facing generally frusto-conical end portion I8 seated in a correspondingly apertured collar or chuck I9. The tool It is retained in the check I9 by means of the tie bolt I5, which is threaded into the tool and is retained in the spindle by means of nuts 20 threaded against the other end of the spindle from that receiving the tool I6.

At the end of the spindle I3 facing the cutting tool head I1 is an annular shoulder 2! against which is press-fitted a sealing or retaining ring 22 having an L-shape cross-section. The ring 22 is rotatable with the spindle I3. Freely fitted within the ring 22 is a retaining ring 23. The ring 23 is secured to the stationary housing II by means of screws 24 of which one is illustrated. The spindle I3 has a generally stepped configuration formed by portions having progressively increasing diameters with annular shoulders 25 and 3I therebetween and spaced apart from one another in a predetermined relationship. Seated on the shoulder 25 of the spindle I3 is an inner race 26 of a group of concentric thrust bearings 21 for journaling the spindle I3 and the bore I2 of the stationary housing II. The inner race 26 is secured to the spindle I3 and rotates therewith, while an outer race 28 remains stationary and is secured to the housing II. Balls 29 are rotatable between the inner race 26 and the outer race 28.

A second group of concentric thrust bearings 30 are seated on the shoulder 3! for further journaling the spindle I3 and the bore I2 of the stationary housing I I. An inner race 32 is seated on the shoulder 3I. The inner race 32 is secured to the spindle I3 and rotates therewith. An outer race 33 remains stationary.

Confined between the stationary outer thrust race 28 of the thrust bearing 2'! and the stationary housing II is a generally cylindrical thrust collar 35. Asimilar thrust collar 35 is seated on the outer thrust race 33. The thrust collars 34 and 35 are rigid non-compressible coupling members.

The thrust collars 34 and 35 have projections 34a and 35a extending therefrom which are in surface contact with a rocker member 31. The rocker member 3 being of hemispherical shape, has a flat end portion in surface contact with the projections 34a and 35a. The rocker member 37 serves to apportion between the two series of bearings the total thrust load. The rocker member 31 is seated in a saddle or cradle 36 which is contained in the housing II.

A series of concentric rocker elements, such as rocker member 31, form a composite rocker 7 member. The rocker elements are spaced apart so as to aiford pivotal movement to each rocker 4 member within a cradle without having the rocker members binding. A projection from each circular collar engages each of the rocker members whereby each rocker member apportions the load between the respective bearings.

To apportion the load, each group of thrust bearings, such as 21 and 30, is provided with a thrust collar. Forces are transmitted from the thrust bearing 2! to the thrust collar 34 and further forces are transmitted from the thrust bearing to the thrust collar 35. The thrust collar 34 and the thrust collar contact a rocker member 3'! so that the thrust load on the rotary member is transmitted to the rocker member 31 through the medium of the thrust collars 34 and 35. The total thrust load transmitted to the rocker member 31 by the collars is the total thrust load imposed on the bearings 21 and 30 from the rotary member I3. The rocker member 31 transmits to the housing II by way of the saddle 33 the total thrust load imposed thereon. The total thrust load transmitted to the rocker member by any collar is directly proportional to the radial distance between the center line of the projection on a collar and the center line of rotation of the rocker member.

Thus, the portion of the thrust load to be transmitted to the housing through each of the bearings is dependent upon and directly proportional 30' to the radial distance between the center line of the projection on the collar and the center line of rotation of the rocker member. Therefore, as shown in Figure 3, to equalize the thrust load for .each bearing, the center line of the projection of each thrust collar must be an equal radial distance to the center line of the rotation of the rocker member 3'1.

In the modified form, as. shown in Figure 4,

' the radial distances between the center of the projections 35a and 33a on the collars 35 and 34, respectively, and the center line of the rotation of the rocker member 37 are not equal and therefore the thrust load of each thrust bearing Ix-is proportional to the radial distance between the primarily rotational bearings.

tain the bearings M in fitted position. A sealing ring 43 is shown fitted around the decreased diamcenter line of the projection of the collar associated therewith and the center line of rotation of the rocker member.

A coolant or lubricating fluid is fed to the spindle assembly through an inlet 38 and the coolant passes therefrom into a passageway 39 and then through an outlet 36.

To further journal the spindle IS in the bore I2 bearings M are provided. The bearings 4I are thrust load, a saddle of ring shape having one an nular end face bottomed against said housing shoulder and having in the other annular end face an annular recess, and a plurality of segmental cylindrical rocker members having cylindrical faces seated in said recess and extending gener- Springs 42 main- 5 ally radially of said saddle and having flat faces providing predetermined surface areas for contact with said respective projections for receiving a thrust load imparted thereto, the bottom of said recess and the faces of the rocker members seated therein having conforming segmental cylindrical portions to provide rocking movement therebetween whereby-the thrust load for each of said bearings is .proportional to the radial distance between the center line of said predetermined sur- 10 face contact area and the center line of rotation of said rocker members.

ARTHUR W. BURKS.

REFERENCES CITED UNITED STATES PATENTS Number Name Date 1,734,223 Melott Nov. 5, 1929 1,956,648 Messinger May 1, 1934 FOREIGN PATENTS Number Country Date 274,401 Germany May 20, 1914 

